He wanted to resign before the election that's just over a month away, in case Republicans made gains in the Senate. The Senate has to approve the new AG. A new AG, someone other than Holder, would have better chance of being held over by Obama's replacement. I think Hillary would want to replace Holder. So, it's better for him to go now, on his own terms, than later. And, he probably has a nice-paying job lined up. Maybe giving six-figure speeches to well-heeled black and Democrat groups.